This invention relates to the field of water-air interactions, specifically the extraction of water from moist air (a mixture of air and water vapor).
Water, especially potable water, is a constant need. Obtaining potable water is a threshold requirement for most human and animal activity. Obtaining potable water can be especially problematic in arid areas. Tremendous effort and expense currently go to drilling wells, building water transport systems, and purifying and desalinating water.
Water is conventionally obtained by purifying existing liquid water. Reverse osmosis, distillation, and filtration are used to purify contaminated water. Desalination is used to produce potable water from sea water. These approaches can be energy-intensive, and require the presence of liquid water as the starting material.
If liquid water is not available, then purification processes are not applicable. Dehumidification by refrigeration can be used to produce liquid water from moist air. Conventional refrigeration processes are very energy-intensive, however. Further, conventional refrigeration processes can involve large and complex machines. Consequently, conventional refrigeration processes are generally not economical for production of potable water.
Accordingly, there is a need for a method and apparatus for obtaining potable water from moist air that does not require the expense or complexity of conventional refrigeration processes.
The present invention provides a method and apparatus for extracting liquid water from moist air using minimal energy input. The method comprises compressing moist air under conditions that foster the condensation of liquid water (i.e., to a pressure where the water originally in the air is more than that representing a relative humidity of 1.0 at the increased pressure). The liquid condensate can be removed for use. Some of the energy required to compress the air can be recovered by allowing the remaining dry air to expand. The decompressed, dried air can be exchanged for a fresh charge of moist air and the process repeated.
The apparatus comprises a compression chamber having a variable internal volume. An intake port allows moist air into the compression chamber. An exhaust port allows dried air out of the compression chamber. A condensation device fosters condensation at the desired conditions. A condensate removal port allows liquid water to be removed.
Advantages and novel features will become apparent to those skilled in the art upon examination of the following description or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.